With a conventional shim, the following drawback is encountered: during rotation of the fan, the shim moves back and forth axially inside its housing and it strikes the drum of the low-pressure compressor repetitively. The repeated strikes of the shim against the drum damage the drum and shorten its lifetime. In general, it is found that an indentation is formed in the drum and constitutes a crack starter zone. This phenomenon is particularly troublesome in that the drum is a part that is relatively expensive.
In order to avoid such a drawback, it is known to provide the shim with two tabs extending respectively from the upstream ends of its branches, these tabs being folded towards each other. The tabs come into abutment against the front face of the blade root when the shim moves downstream. They thus retain the shim before it strikes the drum.
Nevertheless, such tabs tend to unfold under the effect of the thrust forces exerted on them by the blade root. Once unfolded, the tabs no longer act as abutments and the shim is no longer held so it strikes the drum.